Narrow frame screen door latch



M, 1956 A. ERKKILA EMMAN- NARRow FRAME .SCREEN DooR LATCH Filed Feb. zo,195s INVENTOR /ZW- 25 Z6 23 2,770,481 n NARROW FRAME SCREEN DOOR LATCHAndrew Erkkila, Fitchburg,"Mass`., assgiror to Independent LockCompany,Fitchburg, Mass., a corporation of Massachusetts This inventionrelates to screen door latch `sets and more particularly to screen doorlatch sets having a short back set. My invention more specificallyconcerns itself with the problem of installation of a latch on doorframes, such as screen doors or, more recently introduced, screen andstorm doors made of aluminum frames `in-which `the stiles thereof are ofnarrow dimensions, `tohold replaceable screens or glass lights. f l

Eorts by me `toembody ina `frame for t andooref the character describedon'a simple spindleactuatedlatch bolt have encountered dimensionalproblems..in..an ,effort to retain the proper Hoperatingpcondtions.Duelo the extremely short backset" the incorporation of alspring toprojectthe latch boltjof requisiteustiffness .to.orient;a lever handleagainstr sagging `to `a normalpositionhasznot been OUDdL1CCSSL11 lVthgCOIlStuIions, ,heretofore ein-` ployed `to meet therequisite,spring:rigidity:for.spir1dle` Operation whileafordngindependentayieidabiiity, suring long life.` j j j j Accordingly,it is an object of myinvention ,to` provide a latch assembly or door setfor narrow stiles`.involving short backsets of the spindle inwhichuadequate .springt compressibility for spindle operation `and knob,orientation is combined with soft nose yieldability forindependent.latch boltdepression, "Thus,git is annobjectof thisin vention to providea `screen door fsethaving a. spring` projected latch `bolt ,actuated bydouble compression springs, one which has the `requisite:,stiffnesslto.orient the spindle to `a normali4 position, g thereby .not `onlyatoproject` the latch bolt inthe strikeplatebut to maintain` the spindle`and ieverhandle carried thereby. againstsag-` ging in a predeterminedposition`but,also includes afsoft` spring reaction to depressionofmthe`latchbolt, fas :when

it independently is depressedwby ther latch being cammed` by the strikeplate and to combine these..features;ir1.a casing fitting within anarrow stile of avdoorand having a relatively short backset. q x

To attain these objectsand such otherobjects a`s1may appear herein or behereinafter `pointed out, reference` is made `to the accompanying`drawing,formingerspart hereof, in Whichl i Figure 1 is a transversesection showinga .doorlockvset in accordance with my` invention; j,

j Figure 2 isa magnifiedsection,takenonthe line .2,--2

of Figure l; p

Figure 3 `is a View (similar, towFigure 2l with,l the `latch` boltindependently `depressed `by, thelstrike plate; t

Figure 4 s a View similar to Figure l2 showing` the` latch bolt inspindleretracted position;

Figure 5 `is a section taken on the` line 5-'5 of Figure 2;

nited States Patent NO ice ' Figure 8 is a fragmentary section throughthe latch bolt showing a position of the spindle for installation;

`Making reference to the drawing, I illustrate myinvention in connectionwith a fragment of a door10 having a tubular stile 11. Such` frames maybemade ofrsheet metal and preferably extruded aluminum,` serving thedouble purpose of both a storm `door during the winterand as a screendoor during the summer.

The stile 11 has a closure edge 12 providedV with a 'channel 13 in whichthere isseated the end plate 14, to which is ailixed the latch casing15.` The latch casing is tubular and has an abutment wall desirablyshown as a closed end wall 16 and an `open end 17 adjacent thesupporting end plate 14. The latch is assembled into the casing 15`through the opening 17 and for this purpose there is first introducedinto the casing a relatively soft coiled compression spring 18 whichperipherally is guided adjacent the wall 19. Concentric with the spring18 there is introduced aheavy coiled compression spring 20Wl1ich ismaintained centrally of the casing on the lug 21 aixed to the end wall16.

With `the soft and stili springslS and 20 respectively introducedtelescopically into the casing through the mouth 17, there is theninserted in the casing thelatch bolt assembly 22-comprising` the -latchbolt"23 carrying rearwardlythereof the latch shank 24, having spacedbranches 25,5 25, comprising guide arms joinedl toA the latch bolt bythe ring 26, seated-within the 'annular slot127` and longitudinal`extension slot"27ajformed` in the latch bolt` 23 to lie flush `with `thelatch" bolt` and make `a sliding fit within the casing. The guide arms25 extend rearwardly and are joined to each otherby theiend i disk 28,having an aperture 29 centrally thereof through which the stiff spring20 projects.`

`Slidably guided `between the guide arms 25, 25 there isfmounted the camfollower block 30 having rearwardly thereof aboring 3021 into which thestiff spring`20 is centeredafter passingthrough the aperture 29 of theend` disk `28. WThe follower block 30 "is cylindrical, slidablytottwithin the casing, and is formed with guide slots 31 in which the guides25 are mounted for relative slidable `movement of the cam follower andguide armsZS.

With this assembly so `inserted within the casing, a set screw 32,havinga guide pin 33, is projected through the casing to engage theretainer slot 34 formed inthe latch bolt. The slot 34 has its end walls35and 36 spaced from each other to `limit the outward projection of thelatch bolt 23 when the end Wall 35 engages the pin 33, and tolimit theinward movement of the latch bolt when the wall `36 engagefsthe pin 33,assembly being eiected by depressing the latch bolt 23, in whichcondition the set screw 32 is driven home toengage the slot 34. Uponseating the set screw 32, the latch bolt `assembly is projectedoutwardlyand under thecombined iniluence ofthe soft spring "18 and the hardspring 20. The cam follower 30 is slidably guided in the casing 15 toiloat freely along the shank 20, to be guided non-rotationally by thearms 25 in close"adjacency to the apertures 37 through the casing, andis likewise accessible when mounted as shown in Figure linalignment withthe bores 38 formed in the plates 39 ofthe stile.

`Adjacent the plates 39 there are provided escutcheons 40 having bearingcollars 41 arranged rotationally to receive and to center the shank `42of the knob 43 at one end."I The knob 43 carries a spindle 44 connectedtothe knob by the set screw 45. The spindle 44, adjacent its centerrhasa ro'ck shaft cam 46 and a follower seat 47 to receive the nose 48 ofthe cam `follower s i Y Patent is:

When the casing assembly has been positioned in the door stile to alignthe apertures 37 with the bores 38, the latch bolt is depressed to movethe same from the position shown in Figure 2 to the position shown inFigure 3, thereby depressing the disk 28 to clear the apertures 37. Inthis position the -spindle 44` is projected through the escutcheon 4t)to enter the aperture 37. The spindle is provided with a champfered nose49 to wedge the cam follower block 30 against the pressure of the stilspring 20 and to thread the shank through the casing and the opposedframe boring 38a on the'opposite face of the stile through theescutcheon 40, to be engagedby the lever handle 43a and to seatthe shank42a thereof in the escutcheon 41a.

n In this position the cam 46 is seated upon the follower 30, to nestthe nose 48 in the cam seat 47. Thereupon the set screw 1 is driven homein position in a manner well understood.

, By the assembly described, it will be observed that when the latchbolt23 is released it will be projected through the strike 52. Forwithdrawal of the latch bolt, the spindle 44 is oscillated by turnknoboperation, which serves to cam the cam 46 against the angular faces ofthe nose 48 of the cam follower, drawing with it the latch bolt assemblyand projecting the cam follower against the disk 28 and the followerblock 30 against the spring 20. The latch bolt assembly thereby isdepressed against the combined spring resistance of the springs 18 and20. Upon release of the knob, the cam follower nose engages one of thediametrically opposed wings 53, 53 of the carn, to rock the spindle toits normal position under the biasing action of both springs 18 and 20,until the nose 48 is seated in the cam seat 47. Y

When the latch bolt 23 has been withdrawn and then released for openingthe door, the door may be swung into closed position without manualguidance or manual retraction of the latch bolt.

In the projected position, as shown in Figures l and 2, the latch boltmay, upon closing the door, engage the strike plate, depressing thelatch bolt by the camming action of the nose 54 of the strike plate.Inward projection of the latch bolt through thelarms 25 against the disk28 is against the resilient resistance of the soft coiled spring 18,while the stiff spring 20 retains the follower block 30 in engagementwith the cam'46, as more clearly shown in Figure 3.

The oating, sliding'position of the cam follower plug 30 thereby leavesthe latch bolt assembly for independent depression upon striking thestrike plate with'minimum resistance, without interfering with the full'throw necessary for securing retraction. Likewise, theprojectinginiluence of both the stif and soft springs is obtained forthe latch bolt as well as to orient the spindlel and lever handle.carried to a proper position without an undue extension of the casing,thereby permitting a backsetting ofthe centerline of the spindle withinnarrow dimensional limits and making this assembly possible in narrowStiles especially metal tubular frames.

Thus`it will be .observed tht all of the benefits of stiff fspringprojectionA and non-sagging lever handle orientation and soft nosereactionare obtained in very compact form, to secure in a novelassembly'all of the benefits of more extensive casing assemblies. Y

lIt will be understood that locking means for the spindle '44 may bemounted in either of the'escutcheons which may beextended to the outerface of the'door. l

Having Vthus describedmy invention and illustrated its use, what I claimasnew and desire to secure -by Letters 1, IIn arlatch having a latchbolt casing, a latch b olt assembly including a latch bolt shankcomprising spaced t branches guided in said casing ,adjacent the casingwalls; `an independent follower guided by the branches of said for saidlatch bolt shank, a rock shaft spindle positioned between said branchesand transversely extending through said casing to have its opposite endsproject through said casing, to which ends knob means are affixed, saidrock shaft spindle, at its intermediate portion, having camming meanscooperating with said follower, to retract said latch bolt uponoscillation of said rock shaft spindle by sliding said follower, saidlatchl bolt being independently depressible.

2. In a latch, a latch casing including a latch bolt shank lhavingspaced branches guided by the walls of said casing,"a follower guided bythe branches of said shank, independent springs for projecting saidlatch bolt and follower concentrically nested, a rock shaft spindleextending between said branches and through said casing, with theopposed ends of said rock shaft spindle projecting at opposite sides ofsaid casing, said rock shaft spindle, at its intermediate portion,having a camming member engaging said follower, said follower andcamming member having cooperative engaging means whereby oscillatingsaid rock shaft spindle will retract said follower and shank against theinfluence of both springs, said latch bolt being independentlydepressible against one of said springs while the other spring maintainsthe follower in spindle engaging position.

v3. In a latch having a short brackset comprising a tubular latch casingclosed at one end, an end plate supporting the casing adjacent the openend, a pair of concentrically arranged compression springs in saidcasing engaging the closed end thereof, a latch bolt assembly projectedby said springs and guided by said casing, said latch bolt assemblyincluding a shank having spaced branches, a follower guided between saidbranches, said follower being spring projected by one of said springs,said shank being projected by the other of said springs, withindependent relative movement between the shank and follower, a rockshaft spindle transversely positioned through said casing between saidbranches having camming means engaging said follower for conjointretraction of said follower and latch bolt, the latch beingindependently depressible against the action of one of said springswhile the other spring maintains the follower in spindle engagingposition.

4. In a latch having a short backset, a tubular casing having at one endVa closed end wall and a guide opening at the other. end, a pair ofcompression springs bearing against said end wall concentricallypositioned on said end wall and of different stiffness, a latch boltassembly guided by said casing under the influence of both springsguided through said open end, said latch bolt assembly having a shankcomprising wall engaging branches extending in said casing under theinfluence of the weaker of said springs, a floating follower guided bysaid shank, said follower being spring projected bythe stiffer of saidcompression springs, a rock shaft spindle extending through said casingbetween said branches having a camming portion actuating said followerwhereby, upon rockingfsaid spindle, the latch bolt is retracted againstthe-influence of both compression springs and to project the latch boltand follower under such influence, the latch bolt` being` independentlydepressible against the influence of the softer of the compressionsprings.

. 5. In a latch for a short backset comprising a tubular casing, a wallat one end and a guiding Vopening at the other, concentriccompressionvsprings supported against a follower oating between saidguide arms under the influence of said second spring and projectiblethrough said pressure disk to contact said follower and a rock shaft lknob spindle extending through said casing between said guide armshaving a camming portion engaging said 7 5 follower, cooperative noseand seat portions on said follower and cam whereby the latch boltassembly is spring projected under the influence of both`springs, thefollower being under compression of said second spring to orient therock shaft and said latch bolt being independently depressible againstthe inuence of only one of said springs.

References Cited in the le of this patent UNITED STATES PATENTS McKinneyJune 28, 1932 TerMeer Aug. 16, 1932 Voight Feb. 20, 1945 Quigley et al.Aug. 14, 1945 Lickteig Aug. 16, 1949

